The research proposed, utilizing a 10-bed Clinical Research Center and its associated laboratory, will be carried out by members of the full-time staff from the Departments of Medicine, Cardiology, Neurology, Psychiatry, Surgery, Cardiovascular Surgery, Orthopedic Surgery, Neurosurgery and Pathology. The clinical investigations have as their goals the development of methods of assessment, the deepening understanding of fundamental processes at a molecular and cellular level, and improvement of the treatment of the following groups of disorders in children: immunodeficiency states, disturbances of complement metabolism, and collagen diseases; hemoglobinopathies and red cell disorders, leucocyte dysfunction, bone marrow failure; inflammatory bowel disease, liver disease, and cystic fibrosis; disorders of amino acid metabolism; disorders of neuroendocrine function, testicular development and metabolism of steroid hormones, hypoglycemic states, complications of diabetes mellitus; the nephrotic syndrome; Reye's syndrome; complete heart block, regurgitant valvular disease, chronic tachycardia and pulmonary hypertension; epilepsy; disorders of motor development in congenital brain anomalies, of psychological development with social deprivation; parenteral alimentation, and the control of immune responsiveness in allograft recipients.